[Doc]: fix markdown version (#8408)

ZwwWayne · ZwwWayne · commit 13c96834e95c · 2022-09-09T19:50:20.000+08:00
diff --git a/requirements/docs.txt b/requirements/docs.txt
@@ -1,4 +1,5 @@
 docutils==0.16.0
+markdown<3.4.0
 myst-parser
 -e git+https://github.com/open-mmlab/pytorch_sphinx_theme.git#egg=pytorch_sphinx_theme
 sphinx==4.0.2

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,5 @@`
`1`	`1`	`docutils==0.16.0`
	`2`	`+markdown<3.4.0`
`2`	`3`	`myst-parser`
`3`	`4`	`-e git+https://github.com/open-mmlab/pytorch_sphinx_theme.git#egg=pytorch_sphinx_theme`
`4`	`5`	`sphinx==4.0.2`